This invention relates to the testing of standard three-wire ground type electrical outlets. While providing a measure of safety in case of an electrical failure, such outlets present wiring complications not encountered with standard two-wire outlets. No longer may the wires be randomly connected to terminals in the outlet. Unless, the hot, neutral, and ground wires are connected to the proper terminals, the three-wire outlets will present a potential hazard rather than a safety measure.
A quick, easy and inexpensive way to locate such wiring errors is provided by use of this invention. If indicating devices such as lights are connected between each pair of terminals only the lights between the hot terminal and either the ground or neutral terminals will be energized. An improperly wired outlet will be detected when the proper combination of indicators or lights is not displayed.
Other devices have employed this same technique. U.S. Pat. Nos. 3,317,825 and 3,383,588 present devices employing the same circuitry as used in this invention. The circuitry employed does not, however, constitute the gist of this invention. In the invention here disclosed the physical arrangement of the indicator display provides advantages over similar devices. This invention locates the indicator display on one end of the device. A chart showing the meaning of different combinations of energized indicators can then be placed along one side of the device. Easier reference between the chart and the display is therefore possible. The assembly of this invention also demonstrates decided advantages over that of other such devices. Fewer parts are required and those used can generally be easily assembled by snapping or wedging them into place.
An important object of the invention is to provide an inexpensive, easy to use, hand-held tester for use with three-wire electrical outlets. Such a device can then be used by a relatively unskilled technician to locate wiring errors. A further object is to provide such a tester incorporating a display which can be seen from several different directions so that the tester can be utilized with awkwardly positioned outlets. Another object is to provide a circuit tester designed so that a reference chart may be placed proximate to and in alignment with the indicator display, thus allowing direct reference between the chart and the display. A still further object of this invention is to provide a tester which may be constructed from relatively few parts and largely without the use of soldering and extraneous adhesive agents.
These and other objects of this invention will be apparent and can be more fully understood from the following description, which taken in connection with the accompanying drawings, discloses a preferred embodiment of the invention.